DNA and Cell Cycle
DNA and Chromosomes

DNA is in the nucleus of every
living thing.

A Chromosome is coiled DNA.

Humans have 46 chromosomes.
Chromosomes in living things
Black
Mulberry
Plants
308
Agrodiaetus
butterfly
Animals
268
http://www.neok12.com/php/watch.php?v=zX645478027c03150f647502&t=Cell-Division
Cell Cycle

Cells are damaged, lost or die all the time.
New cells must be created to replace them.

Cells make complete copies of themselves
including an exact copy of their DNA.

The steps that cells go through are called
the Cell Cycle and each step is a phase.
New
daughter
cell
Interphase
This is the
normal state of
a cell or the
resting state.
What is Mitosis?
• A cell and its nucleus divide and produce two
identical cells.
• This process is important for growth, to repair
or replace damaged tissue.
• The two daughter cells have the same genetic
information (DNA) as the original cell.
The
phases
of
mitosis
http://www.youtube.com/watch?v=-PMXatafIXc
Sexual Reproduction
Sexual
reproduction is
when
chromosomes
from two different
cells combine,
producing
offspring.
egg
sperm
zygote
What is Meiosis

Meiosis is the type of cell division by which gametes (eggs or
sperm) are formed.

Two divisions result in 4 different daughter cells that have half of
the total number of chromosomes (23).

When an egg and sperm combine during fertilization, the embryo
will have the normal amount of chromosomes (46).
Meiosis
http://scienceforkids.kidipede.com/biology/cells/meiosis.htm
Comparing the two
types of cell division
http://www.pbs.org/wgbh/nova/body/how-cells-divide.html